double pole or single pole rcbos

WallaceP · Jan 12, 2022

What is everyone's thoughts on double pole rcbo's vs single pole, I mostly use Fuse Box these days with the odd Hager board if i'm feeling flush. I usually use the single pole fuse size rcbos. recently I tried the mini double pole rcbos but for the extra cost I think I will go back to using the single pole ones. Just wondering what your guys and girls think of sp vs dp rcbos.

Thanks

timhoward · Jan 13, 2022

Well some advantages of DP are easier IR testing on TNCS setups (if manufacturer allows testing on the outgoing terminals) and ability to totally isolate a circuit for fault diagnostics.
I have occasionally used single pole if budget is tight (and once purchased accidentally!) but prefer double pole.

pc1966 · Jan 14, 2022

Also if you have a TT setup or somewhere like a farm with an up-front delay RCD you only get proper selectivity if you break the N path as well, otherwise a N-E fault will still take out the incomer.

Rockingit · Jan 14, 2022

Personally, I think the question needs to be asked the other way around, especially in 3ph boards - why would you not use a DP device? The Neutral is a line conductor, after all.

pc1966 · Jan 14, 2022

Rockingit said:
Personally, I think the question needs to be asked the other way around, especially in 3ph boards - why would you not use a DP device? The Neutral is a line conductor, after all.

If only they made N-switching RCBOs for 3P boards!

I think Schneider do a N busbar in some of their 3P boards but never had one to play with. Really it is time that was the norm so you just plugged in MCB or RCBO and did not lose a slot or two to get the extra RCD protection.

Rockingit · Jan 14, 2022

pc1966 said:
If only they made N-switching RCBOs for 3P boards!

I think Schneider do a N busbar in some of their 3P boards but never had one to play with. Really it is time that was the norm so you just plugged in MCB or RCBO and did not lose a slot or two to get the extra RCD protection.

Can't remember what thread it was but I posted up the other day about my annoyance with Eaton 3PN RCBO's that are only best used on the right hand side bus bar and rob you of a 1ph (or 3ph by extension) slot.